Organic light-emitting display apparatus and method of manufacturing the same

ABSTRACT

An organic light-emitting display apparatus, including a substrate including a plurality of pixel areas and non-pixel areas in a display area, a plurality of pixel electrodes respectively corresponding to the plurality of pixel areas, a pixel-defining layer including a cover portion and openings, wherein the cover portion covers an edge of each of the plurality of pixel electrodes, and each of the openings exposes a central portion of a pixel electrode among the plurality of pixel electrodes, an auxiliary electrode located such that the auxiliary electrode corresponds to at least a portion of a top surface of the cover portion, and an intermediate layer and a counter electrode, each located in the openings. The pixel-defining layer may have an under-cut structure in which the at least a portion of the top surface of the cover portion is recessed from the auxiliary electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/239,085, filed Jan. 3, 2019, which claims priority to and the benefitof Korean Patent Application No. 10-2018-0010846, filed Jan. 29, 2018,the entire content of both of which is incorporated herein by reference.

BACKGROUND 1. Field

One or more embodiments relate to a method of manufacturing an organiclight-emitting display apparatus.

2. Description of the Related Art

Organic light-emitting display apparatuses have attracted attention asnext-generation display apparatuses due to advantages such as a wideviewing angle, a high contrast ratio, and a fast response time. Inaddition, organic light-emitting display apparatuses do not require aseparate light source, and may operate at a low voltage and have alightweight and thin design.

An organic light-emitting display apparatus includes an organiclight-emitting device (OLED) on a display area, and the OLED includes apixel electrode and a counter electrode that face each other, and anintermediate layer located between the pixel electrode and the counterelectrode and including an emission layer.

SUMMARY

Embodiments are directed to an organic light-emitting display apparatus,including a substrate including a plurality of pixel areas and non-pixelareas in a display area, a plurality of pixel electrodes respectivelycorresponding to the plurality of pixel areas, a pixel-defining layerincluding a cover portion and openings, wherein the cover portion coversan edge of each of the plurality of pixel electrodes, and each of theopenings exposes a central portion of a pixel electrode among theplurality of pixel electrodes, an auxiliary electrode located such thatthe auxiliary electrode corresponds to at least a portion of a topsurface of the cover portion, and an intermediate layer and a counterelectrode, each located in the openings. The pixel-defining layer mayhave an under-cut structure in which the at least a portion of the topsurface of the cover portion is recessed from the auxiliary electrode.

The intermediate layer may include an emission layer, a lower functionallayer located under the emission layer, and an upper functional layerlocated over the emission layer. At least a portion of the intermediatelayer may be located over the auxiliary electrode. At least a portion ofthe lower functional layer located over the auxiliary electrode may bespaced apart from a portion of the lower functional layer located insidethe openings.

The lower functional layer may include at least one of a hole injectionlayer and a hole transport layer.

The intermediate layer may include an organic emission layer, a lowerfunctional layer located under the organic emission layer, and an upperfunctional layer located over the organic emission layer. A thickness ofthe auxiliary electrode may be greater than a thickness of the lowerfunctional layer.

The auxiliary electrode may have a mesh form with through-holescorresponding to the openings of the pixel-defining layer.

A width of the counter electrode may be greater than a width of theintermediate layer.

An end portion of the counter electrode may extend toward and contactthe auxiliary electrode.

The auxiliary electrode may include at least one of molybdenum (Mo) andtitanium (Ti), and the counter electrode may include Yb/Ag:Mg/ITO.

A plurality of thin-film transistors (TFTs) electrically connected tothe plurality of pixel electrodes may be on the substrate.

The organic light-emitting display apparatus may further include athin-film encapsulation layer located on the display area. The thin-filmencapsulation layer may include at least one inorganic film and at leastone organic film.

Embodiments are also directed to a method of manufacturing an organiclight-emitting display apparatus, including providing a substrate onwhich a plurality of pixel electrodes are formed, and forming apixel-defining layer including a cover portion and openings. The coverportion may cover an edge of an adjacent pixel electrode from among theplurality of pixel electrodes. The openings may respectively expose acentral portion of each of the plurality of pixel electrodes. The methodfurther includes forming an auxiliary electrode such that the auxiliaryelectrode corresponds to at least a portion of a top surface of thecover portion, forming, by etching a side surface of the cover portion,an under-cut structure in which the at least a portion of the topsurface of the cover portion is recessed from the auxiliary electrode,and forming a first masking layer such that a first pixel electrode fromamong the plurality of pixel electrodes is exposed, and then forming, onthe first pixel electrode, a first intermediate layer and a firstcounter electrode.

Forming the auxiliary electrode and forming the under-cut structure maybe performed using a same photoresist pattern.

The pixel-defining layer may include an organic material. Etching theside surface of the cover portion may be performed by dry etching usingan oxygen plasma.

The pixel-defining layer may include an inorganic material. Etching theside surface of the cover portion may be performed by dry etching usinga SF₆ gas.

The first intermediate layer includes an emission layer, a lowerfunctional layer located under the emission layer, and an upperfunctional layer located over the emission layer. A thickness of theauxiliary electrode may be greater than a thickness of the lowerfunctional layer.

The first intermediate layer may include an emission layer, a lowerfunctional layer located under the emission layer, and an upperfunctional layer located over the emission layer. At least a portion ofthe first intermediate layer may be located over the auxiliaryelectrode. At least a portion of the lower functional layer located overthe auxiliary electrode may be spaced apart from a portion of the lowerfunctional layer located inside the openings.

The lower functional layer may include at least one of a hole injectionlayer and a hole transport layer.

An end portion of the first counter electrode may extend toward andcontact the auxiliary electrode.

The method may further include removing the first masking layer by alift-off process, forming a second masking layer such that a secondpixel electrode from among the plurality of pixel electrodes is exposed,forming, on the second pixel electrode, a second intermediate layer anda second counter electrode, removing the second masking layer by alift-off process, forming a third masking layer such that a third pixelelectrode from among the plurality of pixel electrodes is exposed, andforming, on the third pixel electrode, a third intermediate layer and athird counter electrode.

The substrate may include a plurality of thin-film transistors (TFTs)electrically connected to the plurality of pixel electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

Features will become apparent to those of skill in the art by describingin detail exemplary embodiments with reference to the attached drawingsin which:

FIG. 1 illustrates a plan view of an organic light-emitting displayapparatus according to an embodiment;

FIGS. 2A and 2B illustrate equivalent circuit diagrams of a pixel,according to embodiments;

FIG. 3 illustrates a cross-sectional view of an organic light-emittingdisplay apparatus according to an embodiment;

FIG. 4 illustrates an enlarged cross-sectional view illustrating portionI of FIG. 3;

FIG. 5 illustrates a plan view of the organic light-emitting displayapparatus of FIG. 3 as seen from a direction Z;

FIG. 6 illustrates a modification of FIG. 5;

FIGS. 7A and 7B illustrate cross-sectional views of a circuit devicelayer of a display apparatus, according to embodiments;

FIGS. 8 through 17 illustrate cross-sectional views for explainingstages of a method of manufacturing the organic light-emitting displayapparatus of FIG. 3, according to an embodiment; and

FIG. 18 illustrates a cross-sectional view of an organic light-emittingdisplay apparatus according to another embodiment.

DETAILED DESCRIPTION

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, they may be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey exemplary implementations to those skilled in the art.

In the drawing figures, the dimensions of layers and regions may beexaggerated for clarity of illustration. It will also be understood thatwhen a layer or element is referred to as being “on” another layer orsubstrate, it can be directly on the other layer or substrate, orintervening layers may also be present. Further, it will be understoodthat when a layer is referred to as being “under” another layer, it canbe directly under, and one or more intervening layers may also bepresent. In addition, it will also be understood that when a layer isreferred to as being “between” two layers, it can be the only layerbetween the two layers, or one or more intervening layers may also bepresent. Like reference numerals refer to like elements throughout.

FIG. 1 illustrates a plan view of an organic light-emitting displayapparatus 1 according to an embodiment.

Referring to FIG. 1, the organic light-emitting display apparatus 1 mayinclude a display area DA and a peripheral area PA that is a non-displayarea. The display area DA, on which pixels P each including an organiclight-emitting device (OLED) are located, provides a predeterminedimage. The peripheral area PA, which does not provide an image, mayinclude a scan driver and a data driver for applying electrical signalsto the pixels P of the display area DA and power supply lines forsupplying power such as a driving voltage and a common voltage.

FIGS. 2A and 2B illustrate equivalent circuit diagrams of each pixel Paccording to embodiments.

Referring to FIG. 2A, each pixel P includes a pixel circuit PC connectedto a scan line SL and a data line DL and an OLED connected to the pixelcircuit PC.

The pixel circuit PC may include a driving thin-film transistor (TFT)T1, a switching TFT T2, and a storage capacitor Cst. The switching TFTT2 may be connected to the scan line SL and the data line DL. Theswitching TFT T2 may apply a data signal Dm, input through the data lineDL according to a scan signal Sn input through the scan line SL, to thedriving TFT T1.

The storage capacitor Cst may be connected to the switching TFT T2 and adriving voltage line PL. The storage capacitor Cst may store a voltagecorresponding to a difference between a voltage received from theswitching TFT T2 and a driving voltage ELVDD supplied to the drivingvoltage line PL.

The driving TFT T1 may be connected to the driving voltage line PL andthe storage capacitor Cst. The driving TFT T1 may control a drivingcurrent flowing through the OLED from the driving voltage line PL inaccordance with a value of the voltage stored in the storage capacitorCst. The organic light-emitting display apparatus may emit light havinga predetermined luminance using the driving current.

The pixel P illustrated in FIG. 2A includes two TFTs and one storagecapacitor Cst. In some implementation, the pixel P may include adifferent number of TFTs.

Referring to FIG. 2B, the pixel circuit PC may include the driving andswitching TFTs T1 and T2, a compensation TFT T3, a first initializationTFT T4, a first emission control TFT T5, a second emission control TFTT6, and a second initialization TFT T7.

A drain electrode of the driving TFT T1 may pass through the secondemission control TFT T6 to be electrically connected to the OLED. Thedriving TFT T1 may receive the data signal Dm according to a switchingoperation of the switching TFT T2 and may supply driving current to theOLED.

A gate electrode of the switching TFT T2 may be connected to the scanline SL. A source electrode of the switching TFT T2 may be connected tothe data line DL. A drain electrode of the switching TFT T2 may beconnected to a source electrode of the driving TFT T1 and may passthrough the first emission control TFT T5 and to be connected to thedriving voltage line PL.

The switching TFT T2 may be turned on according to the scan signal Sn(referred to as first scan signal) received through the scan line SL.The switching TFT T2 may perform a switching operation of applying thedata signal Dm transmitted through the data line DL to the sourceelectrode of the driving TFT T1.

A gate electrode of the compensation TFT T3 may be connected to a firstscan line SLn. A source electrode of the compensation TFT T3 may beconnected to the drain electrode of the driving TFT T1, and may passthrough the second emission control TFT T6 to be connected to a pixelelectrode of the OLED. A drain electrode of the compensation TFT T3 maybe connected to any one electrode of the storage capacitor Cst, a sourceelectrode of the first initialization TFT T4, and a gate electrode ofthe driving TFT T1. The compensation TFT T3 may be turned on accordingto the first scan signal Sn received through the scan line SL. The firstTFT T3 may perform diode-connection on the driving TFT T1 by connectingthe gate electrode and the drain electrode of the driving TFT T1.

A gate electrode of the first initialization TFT T4 may be connected toa second scan line SLn−1. A drain electrode of the first initializationTFT T4 may be connected to an initialization voltage line VL. The sourceelectrode of the first initialization TFT T4 may be connected to any oneelectrode of the storage capacitor Cst, the drain electrode of thecompensation TFT T3, and the gate electrode of the driving TFT T1. Thefirst initialization TFT T4 may be turned on according to a second scansignal Sn−1 received through the second scan line SLn−1. The firstinitialization TFT T4 may perform an initialization operation ofapplying an initialization voltage VINT to the gate electrode of thedriving TFT T1 to initialize a voltage of the gate electrode of thedriving TFT T1.

A gate electrode of the first emission control TFT T5 may be connectedto an emission control line EL. A source electrode of the first emissioncontrol TFT T5 may be connected to the driving voltage line PL. A drainelectrode of the first emission control TFT T5 may be connected to thesource electrode of the driving TFT T1 and the drain electrode of theswitching TFT T2.

A gate electrode of the second emission control TFT T6 may be connectedto the emission control line EL. A source electrode of the secondemission control TFT T6 may be connected to the drain electrode of thedriving TFT T1 and the source electrode of the compensation TFT T3. Adrain electrode of the second emission control TFT T6 may beelectrically connected to the pixel electrode of the OLED. The firstemission control TFT T5 and the second emission control TFT T6 may besimultaneously turned on according to an emission control signal Enreceived through the emission control line EL. Thus, the driving voltageELVDD may be applied to the OLED and driving current may flow throughthe OLED.

A gate electrode of the second initialization TFT T7 may be connected toa third scan line SLn+1. A source electrode of the second initializationTFT T7 may be connected to the pixel electrode of the OLED. A drainelectrode of the second initialization TFT T7 may be connected to theinitialization voltage line VL. The second initialization TFT T7 may beturned on according to a third scan signal Sn+1 received through thethird scan line SLn+1. The second initialization TFT T7 may initializethe pixel electrode of the OLED.

Another electrode of the storage capacitor Cst may be connected to thedriving voltage line PL. Any one electrode of the storage capacitor Cstmay be connected to the gate electrode of the driving TFT T1, the drainelectrode of the compensation TFT T3, and the source electrode of thefirst initialization TFT T4.

A counter electrode of the OLED may receive a common power supplyvoltage ELVSS. The OLED may receive the driving current from the drivingTFT T1 to emit light.

In some implementations, the number of TFTs and storage capacitors andthe circuit design may be varied.

FIG. 3 illustrates a cross-sectional view of a display apparatusaccording to an embodiment. FIG. 4 illustrates an enlargedcross-sectional view of a portion I of FIG. 3.

Referring to FIG. 3, the display area DA may include first through thirdpixel areas PA1, PA2, and PA3 on which pixels, for example, firstthrough third pixels P1, P2, and P3, are located. The display area D1may include a non-pixel area NPA between adjacent pixel areas. The term‘pixel area’ used herein refers to an area where light is actuallyemitted, that is, a light-emitting area.

The first through third pixels P1, P2, and P3 may emit light ofdifferent colors. For example, the first pixel P1 may emit red light,the second pixel P2 may emit green light, and the third pixel P3 mayemit green light. In some implementations, the display area DA mayfurther include a fourth pixel that emits white light.

A substrate 100 may include a suitable material such as a glassmaterial, or a plastic material (e.g., polyethylene terephthalate (PET),polyethylene naphthalate (PEN), or polyimide). Flexibility when thesubstrate 100 is formed of a plastic material may be greater thanflexibility when the substrate 100 is formed of a glass material.

A circuit device layer 110 including the pixel circuit PC may beprovided on the substrate 100. The pixel circuit PC may include a TFTand a storage capacitor as described with reference to FIGS. 2A and 2B.Layers such as, for example, a semiconductor layer and electrode layersof the TFT and the storage capacitor, may be located with an insulatinglayer therebetween. The pixel circuit PC may located with respect toeach of the first through third pixels P1, P2, and P3.

The first through third pixels P1, P2, and P3 may respectively includefirst through third OLEDs OLED1, OLED2, and OLED3 electrically connectedto the pixel circuits PC. Each of the first through third OLEDs OLED1,OLED2, and OLED3 may include a pixel electrode, an intermediate layerincluding an emission layer, and a counter electrode.

OLED1 may include a first pixel electrode 211, a first intermediatelayer 221, and a first counter electrode 231. T OLED2 may include asecond pixel electrode 212, a second intermediate layer 222, and asecond counter electrode 232. OLED3 may include a third pixel electrode213, a third intermediate layer 223, and a third counter electrode 233.

An end portion of each of the first through third pixel electrodes 211,212, and 213 may be covered by a pixel-defining layer 120. A centralportion of each of the first through third pixel electrodes 211, 212,and 213 may be exposed through an opening OP1 and may contact each ofthe first through third intermediate layers 221, 222, and 223 throughthe opening OP1.

For example, the pixel-defining layer 120 may include a cover portion120 c that covers the end portion of each of the first through thirdpixel electrodes 211, 212, and 213 and the opening OP1 through which thecentral portion of each of the first through third pixel electrodes 211,212, and 213 is exposed.

Each of the first through third intermediate layers 221, 222, and 223including the emission layer may be located on a portion of each of thefirst through third pixel electrodes 211, 212, and 213 exposed by thepixel-defining layer 120. The first through third counter electrodes231, 232, and 233 may be respectively located on the first through thirdintermediate layers 221, 222, and 223. Light may be emitted from theintermediate layer between the pixel electrode and the counterelectrode. Accordingly, each pixel area is defined by the pixel-defininglayer 120.

The pixel-defining layer 120 may include an organic material or aninorganic material. When the pixel-defining layer 120 includes anorganic material, the pixel-defining layer 120 may include at least oneorganic insulating material selected from polyimide, polyamide, acrylicresin, benzocyclobutene, and phenolic resin. When the pixel-defininglayer 120 includes an inorganic material, the pixel-defining layer 120may have a single-layer structure or a multi-layer structure includingsilicon oxide (SiOx), silicon nitride (SiNx), and/or silicon oxynitride(SiON).

The auxiliary electrode 130 may be located on the cover portion 120 c ofthe pixel-defining layer 120. For example, the pixel electrode 130 maybe located to correspond to the non-pixel area NPA between adjacentpixel areas of the first through third pixel areas PA1, PA2, and PA3.The auxiliary electrode 130 may be connected to a common power supplyline and may apply the common power supply voltage ELVSS to each of thefirst through third pixels P1, P2, and P3.

The auxiliary electrode 130 may include a conductive material, forexample, a metal or a transparent conductive oxide (TCO). The auxiliaryelectrode 130 may have a single-layer structure or a multi-layerstructure. In some implementations, the auxiliary electrode 130 mayinclude a metal such as molybdenum (Mo) or titanium (Ti).

The pixel-defining layer 120 may have an under-cut structure in which anupper portion of the pixel-defining layer 120 on which the auxiliaryelectrode 130 is located is recessed from the auxiliary electrode 130.For example, the pixel-defining layer 120 may include the under-cutstructure in which at least a part of a top surface of the cover portion120 c of the pixel-defining layer 120 is recessed from the auxiliaryelectrode 130. The under-cut structure may be used to minimize defectsof the first through third OLEDs OLED1, OLED2, and OLED3, as will bedescribed below.

The first through third pixel electrodes 211, 212, and 213 may haveisland shapes respectively corresponding to the first through thirdpixel areas PA1, PA2, and PA3. The first through third pixel electrodesmay located on the circuit device layer 110 so as to be spaced apartfrom one another.

Each of the first through third pixel electrodes 211, 212, and 213 maybe a reflective electrode or a transmissive electrode.

When each of the first through third pixel electrodes 211, 212, and 213is a reflective electrode, each of the first through third pixelelectrodes 211, 212, and 213 may include a reflective film formed ofsilver (Ag), magnesium (Mg), aluminum (Al), platinum (Pt), palladium(Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium(Cr), or a compound thereof. In some implementations, each of the firstthrough third pixel electrodes 211, 212, and 213 may include areflective film, and a TCO film located over or/and under the reflectivefilm. In an embodiment, each of the first through third pixel electrodes211, 212, and 213 may have a three-layer structure formed of ITO/Ag/ITO.

When each of the first through third pixel electrodes 211, 212, and 213is a transmissive electrode, each of the first through third pixelelectrodes 211, 212, and 213 may be a TCO layer. In someimplementations, each of the first through third pixel electrodes 211,212, and 213 may be in a form of a metal thin film including silver (Ag)or an Ag alloy, or may have a multi-layer structure including a metalthin film and a TCO layer formed on the metal thin film.

The first through third intermediate layers 221, 222, and 223 may haveisland shapes located to respectively correspond to the first throughthird pixel areas PA1, PA2, and PA3. The first through thirdintermediate layers 221, 222, and 223 may be spaced apart from oneanother. The first through third intermediate layers 221, 222, and 223may be respectively located on the first through third pixel electrodes211, 212, and 213 exposed through the openings OP1 of the pixel-defininglayer 120. At least a part of each of the first through thirdintermediate layers 221, 222, and 223 may extend along a side surface ofthe opening OP1 of the pixel-defining layer 120 and extend over theauxiliary electrode 130.

Referring to FIGS. 3 and 4, the first intermediate layer 221 may includean emission layer 221 b. The emission layer 221 b may be an organicemission layer that emits, for example, red light. The firstintermediate layer 221 may further include a lower functional layer 221a located under the emission layer 221 b and/or an upper functionallayer 221 c located over the emission layer 221 b. The lower functionallayer 221 a may include a hole injection layer (HIL) and/or a holetransport layer (HTL). The upper functional layer 221 c may include anelectron transport layer (ETL) and/or an electron injection layer (EIL).The lower functional layer 221 a and/or the upper functional layer 221 cmay help the emission layer 221 b to efficiently emit light by matchingan energy level of the emission layer 221 b to the first pixel electrode211 or the first counter electrode 231.

Each emission layer may be formed of suitable light-emitting materials.For example, each emission layer may be formed to include a host and adopant. The dopant may be a fluorescent dopant or a phosphorescentdopant.

For example, the host may be Alq3C 4,4′-N,N′-dicarbazole-biphenyl (CBP),9,10-di(naphthalene-2-yl)anthracene (ADN), or distyrylarylene (DSA).

An HIL material may be, for example, a phthalocyanine compound such ascopper phthalocyanine, 4,4′,4″-tris(3-methylphenylphenylamino)(m-MTDATA), N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (NPB), TDATA,2-TNATA, polyaniline/dodecylbenzenesulfonic acid (Pani/DBSA),poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS),polyaniline/camphorsulfonic acid (Pani/CSA), orpolyaniline/poly(4-styrenesulfonate) (PANI/PSS).

An HTL material may be, for example, a carbazole derivative such asN-phenylcarbazole or polyvinyl carbazole, an amine derivative having afused aromatic ring such as, NPB,N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine (TPD)or N,N′-di(naphthalene-1-yl)-N,N′-diphenyl benzidine (α-NPD), or4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA). From among these, forexample, TCTA may prevent the diffusion of excitons from the emissionlayer, in addition to performing a hole transport function.

An ETL material may be, for example, a quinoline derivative such astris(8-quinolinolate)aluminum (Alq3), TAZ, or Balq.

An EIL material may be, for example LiF, NaClC CsF, Li₂O, or BaO.

Each of the lower functional layer 221 a and the upper functional layer221 c may have a single-layer structure or a multi-layer structure. Insome implementations, the lower functional layer 221 a and/or the upperfunctional layer 221 c may be omitted.

The lower functional layer 221 a, the emission layer 221 b, and theupper functional layer 221 c on the auxiliary electrode 130 may have aforward taper shape such that a side surface of each of the lowerfunctional layer 221 a, the emission layer 221 b, and the upperfunctional layer 221 c has a predetermined angle as shown in FIG. 4. Insome implementations, the upper functional layer 221 c may extenddownwardly along a side surface of the emission layer 221 b or a sidesurface of the lower functional layer 221 a. In some implementations,the emission layer 221 b may be deposited to extend downwardly along aside surface of the lower functional layer 221 a.

As described above, the pixel-defining layer 120 may have the under-cutstructure in which an upper portion of the pixel-defining layer 120 onwhich the auxiliary electrode 130 is located is recessed from theauxiliary electrode 130. Due to the under-cut structure, the lowerfunctional layer 221 a located under the emission layer 221 b and theemission layer 221 b may each include a portion located over theauxiliary electrode 130 and a portion located inside the opening OP1.

If the auxiliary electrode 130 and the pixel-defining layer 120 were tonot have the under-cut structure, the lower functional layer 221 a couldcontinuously extend from the inside of the opening OP1 to the top of theauxiliary electrode 130. In this case, the first counter electrode 231could be connected to the lower functional layer 221 a, and electronsinjected through the first counter electrode 231 could flow into thefirst pixel electrode 211 through the lower functional layer 221 a,thereby leading to undesirable lateral leakage.

However, in the present embodiment, the pixel-defining layer 120 has theunder-cut structure in which the pixel-defining layer 120 is recessedfrom the auxiliary electrode 130. Accordingly, the portion of the lowerfunctional layer 221 a located over the auxiliary electrode 130 and theportion of the lower functional layer 221 a located inside the openingOP1 may be spaced apart from each other, thereby helping to preventlateral leakage.

In the present embodiment, a thickness t₁ of the auxiliary electrode 130may be greater than a thickness t2 of the lower functional layer 221 a.When the thickness t₁ of the auxiliary electrode 130 is greater than thethickness t2 of the lower functional layer 221 a, the portion of thelower functional layer 221 a located over the auxiliary electrode 130and the portion of the lower functional layer 221 a located inside theopening OP1 may not connect to each other during deposition.

In the present embodiment, a distance d of the cover portion 120 c ofthe pixel-defining layer 120 that is concaved inwardly from an endportion of the auxiliary electrode 130 may be greater than the thicknesst2 of the lower functional layer 221 a. Accordingly, the portion of thelower functional layer 221 a located over the auxiliary electrode 130and the portion of the lower functional layer 221 a located inside theopening OP1 may not connect to each other during deposition.

In the present embodiment, at least a part of the emission layer 221 band/or the upper functional layer 221 c may also be formed such that aportion located over the auxiliary electrode 130 and a portion locatedinside the opening OP1 are spaced apart from each other. Suitablemodifications may be made according to a thickness of the auxiliaryelectrode 130 and a distance of the cover portion 120 c that is concavedinwardly from an end portion of the auxiliary electrode 130.

Referring back to FIG. 3, the second intermediate layer 222 may includean organic emission layer that emits green light. The third intermediatelayer 223 may include an organic emission layer that i that emits bluelight. Each of the second intermediate layer 222 and the thirdintermediate layer 223 may further include a lower functional layerlocated under the emission layer and/or an upper functional layerlocated over the emission layer. The lower functional layer may be anHIL and/or an HTL, and the upper functional layer may be an ETL and/oran EIL. In each of the second intermediate layer 222 and the thirdintermediate layer 223, a portion of the lower functional layer locatedover the auxiliary electrode 130 and a portion of the lower functionallayer located inside the opening OP1 may be spaced apart from eachother, and a thickness of the auxiliary electrode 130 may be greaterthan a thickness of the lower functional layer.

Thicknesses of the first through third intermediate layers 221, 222, and223 may be different from one another. The first through thirdintermediate layers 221, 222, and 223 are independently/individuallypatterned in a subsequent process. Accordingly, materials andthicknesses of functional layers of the first through third intermediatelayers 221, 222, and 223 may be different from one another.

The first through third counter electrodes 231, 232, and 233 may haveisland shapes to respectively correspond to the first through thirdpixel areas PA1, PA2, and PA3, and may be spaced apart from one another.The first through third counter electrodes 231, 232, and 233 may berespectively located on the first through third intermediate layers 221,222, and 223.

Widths W21, W22, and W23 of the first through third counter electrodes231, 232, and 233 may be greater than widths W11, W12, and W13 of thefirst through third intermediate layers 221, 222, and 223. End portionsof the first through third counter electrodes 231, 232, and 233 mayextend farther toward the auxiliary electrode 130 than the first throughthird intermediate layers 221, 222, and 223 and may contact theauxiliary electrode 130.

Each of the first through third counter electrodes 231, 232, and 233 maybe a transmissive electrode or a reflective electrode. Each of the firstthrough third counter electrodes 231, 232, and 233 may include at leastone of silver (Ag), magnesium (Mg), aluminum (Al), ytterbium (Yb),calcium (Ca), lithium (Li), and gold (Au). For example, each of thefirst through third counter electrodes 231, 232, and 233 may have asingle or multi-layer structure including at least one from among Ag,Mg, Al, Yb, Ca, LiF/Ca, LiF/Al, Al, and Au. In some embodiments, each ofthe first through third counter electrodes 231, 232, and 233 may includea TCO film. In an implementation, each of the first through thirdcounter electrodes 231, 232, and 233 may include a metal thin filmincluding Ag and Mg. The amount of Ag contained in each of the firstthrough third counter electrodes 231, 232, and 233 may be greater thanthe amount of Mg. In another implementation, each of the first throughthird counter electrodes 231, 232, and 233 may have a multi-layerstructure formed of Yb/Ag:Mg/ITO.

Each of the first through third counter electrodes 231, 232, and 233including any of the above materials may be a transmissive electrodewith a small thickness or may be a reflective electrode with a largethickness. For example, each of the first through third counterelectrodes 231, 232, and 233 may be a transmissive electrode obtained byforming a metal including Ag and Mg to a thickness ranging from about 10Å to about 15 Å, or may be a reflective electrode obtained by forming ametal to a thickness equal to or greater than about 50 nm.

The first through third counter electrodes 231, 232, and 233 may becovered by a passivation layer that prevents damage to the first throughthird counter electrodes 231, 232, and 233 and layers located under thefirst through third counter electrodes 231, 232, and 233 during amanufacturing process. The passivation layer may include an inorganicinsulating material such as SiOx, SiNx, and/or SiON, and may have asingle or multi-layer structure.

The first through third counter electrodes 231, 232, and 233 havingisland shapes and spaced apart from one another may be electricallyconnected to one another through the auxiliary electrode 130, and may beconnected to the common power supply line and may receive the commonpower supply voltage ELVSS.

FIG. 5 illustrates a plan view of the organic light-emitting displayapparatus of FIG. 3 seen in a direction Z. FIG. 6 illustrates amodification of FIG. 5. For convenience of explanation, only thepixel-defining layer 120, the auxiliary electrode 130, and the firstthrough third counter electrodes 231, 232, and 233 from among elementsof the organic light-emitting display apparatus of FIG. 3 are shown inFIGS. 5 and 6.

Referring to FIG. 5, in some embodiments, the auxiliary electrode 130may have a through-hole hi corresponding to the opening OP1 of thepixel-defining layer 120. The auxiliary electrode may be located tocover the cover portion 120 c of the pixel-defining layer 120. Forexample, the auxiliary electrode 130 may have a mesh shape with aplurality of the through-holes hi.

The auxiliary electrode 130 may be located on the pixel-defining layer120 of the non-pixel area NPA and may partially overlap and directlycontact the first through third counter electrodes 231, 232, and 233respectively located on the first through third pixel areas PA1, PA2,and PA3.

Referring to FIG. 6, in an embodiment, the auxiliary electrode 130 mayhave a stripe shape on the non-pixel area NPA. A plurality of theauxiliary electrodes 130 each having a stripe shape may be located onthe pixel-defining layer 120 of the non-pixel area NPA. The auxiliaryelectrodes 130 may partially overlap and directly contact the firstthrough third counter electrodes 231, 232, and 233 respectively locatedon the first through third pixel areas PA1, PA2, and PA3.

The auxiliary electrode 130 may be located on the pixel-defining layer120 of the non-pixel area NPA and may partially overlap and directlycontact the first through third counter electrodes 231, 232, and 233. Insome implementations, the auxiliary electrode 130 may be patterned intoa suitable shape other than a mesh shape or a stripe shape of FIG. 5 or6.

FIGS. 7A and 7B illustrate cross-sectional views of the circuit devicelayer 110 of an organic light-emitting display apparatus according toembodiments.

Referring to FIG. 7A, the driving TFT T1 may include a drivingsemiconductor layer A1, a driving gate electrode G1, a driving sourceelectrode S1, and a driving drain electrode D1. The switching TFT T2 mayinclude a switching semiconductor layer A2, a switching gate electrodeG2, a switching source electrode S2, and a switching drain electrode D2.The storage capacitor Cst may include first and second storage capacitorplates CE1 and CE2.

A gate insulating layer 103 may be located between the driving andswitching semiconductor layers A1 and A2 and the driving and switchinggate electrodes G1 and G2. A dielectric layer 105 may be located betweenthe first and second storage capacitor plates CE1 and CE2. An interlayerinsulating layer 107 may be located between the driving and switchinggate electrodes G1 and G2 and the driving and switching source/drainelectrodes S1, D1, S2, and D2. A planarization insulating layer 109 maybe located on the driving and switching source/drain electrodes S1, D1,S2, and D2.

The gate insulating layer 103 may have a single layer structure or amulti-layer structure and may include an inorganic material such as SiNxand/or silicon oxide (SiOx). Each of the dielectric layer 105 and theinterlayer insulating layer 107 may include an inorganic material suchas SiOx and/or Al₂O₃. The planarization insulating layer 109 mayinclude, for example, an organic material including a general-purposepolymer such as polymethylmethacrylate (PMMA) or polystyrene (PS), apolymeric derivative having a phenol-based group, an acryl-basedpolymer, an imide-based polymer, an arylether-based polymer, anamide-based polymer, a fluorine-based polymer, a p-xylene-based polymer,a vinyl alcohol-based polymer, and/or a blend thereof.

In some implementations, the storage capacitor Cst and the driving andswitching TFTs T1 and T2 may overlap each other and the driving gateelectrode G1 may be the first storage capacitor plate CE1 in FIG. 7A

Referring to FIG. 7B, in some implementations, the storage capacitor Cstmay not overlap the driving TFT T1. For example, the first storagecapacitor plate CE1 and the driving gate electrode G1 may include thesame material. The second storage capacitor plate CE2 and the drivingsource and drain electrodes S1 and D1 may include the same material. Theinterlayer insulating layer 107 may be located between the first andsecond storage capacitor plates CE1 and CE2,

In some implementations, as described with reference to FIGS. 7A and 7B,the driving and switching gate electrodes G1 and G2 of the driving andswitching TFTs T1 and T2 may be respectively located over the drivingand switching semiconductor layers A1 and A2. In some implementations,the driving and switching gate electrodes G1 and G2 may be respectivelylocated under the driving and switching semiconductor layers A1 and A2.According to positions of the driving and switching gate electrodes G1and G2, the driving and switching semiconductor layers A1 and A2 may belocated directly over the inorganic buffer layer 101 in someembodiments, and the driving and switching gate electrodes G1 and G2 maybe located directly over the inorganic buffer layer 101 in someembodiments.

FIGS. 8 through 17 illustrate cross-sectional views of stages of aprocess of manufacturing the organic light-emitting display apparatusaccording to an embodiment.

Referring to FIG. 8, the circuit device layer 110 including the pixelcircuits PC may be formed on the substrate 100, and the first throughthird pixel electrodes 211, 212, and 213 may be formed on the circuitdevice layer 110. The first through third pixel electrodes 211, 212, and213 may be formed to respectively correspond to the first through thirdpixel areas PA1, PA2, and PA3. For example, the first through thirdpixel electrodes 211, 212, and 213 may be formed by forming apreliminary pixel electrode layer on the circuit device layer 100 andthen patterning the preliminary pixel electrode layer. A material of thesubstrate 100 and materials of the first through third pixel electrodes211, 212, and 213 have been described with reference to FIG. 3, and thusa explanation thereof will not be repeated.

The pixel-defining layer 120 having the openings OP1 through which thefirst through third pixel electrodes 211, 212, and 213 are exposed maybe formed by forming an insulating material layer on the first throughthird pixel electrodes 211, 212, and 213 and then patterning theinsulating material layer.

The pixel-defining layer 120 may include an organic material or aninorganic material. When the pixel-defining layer 120 includes anorganic material, the pixel-defining layer 120 may include at least oneorganic insulating material selected from polyimide, polyamide, acrylicresin, benzocyclobutene, and phenolic resin. When the pixel-defininglayer 120 includes an inorganic material, the pixel-defining layer 120may have a single layer structure or multi-layer structure includingSiOx, SiNx, and/or SiON.

Referring to FIG. 9, an auxiliary electrode 130 may be formed over thecover portion 120 c of the pixel-defining layer 120 or the non-pixelarea NPA. The auxiliary electrode 130 may include a conductive material,for example, a metal or TCO. The auxiliary may have a single ormulti-layer structure. In some embodiments, the auxiliary electrode 130may include a metal such as Mo or Ti.

The auxiliary electrode 130 may be formed by forming a conductivematerial layer over the entire substrate 100, forming a photoresistpattern PR on the conductive material layer, and then performingetching. The etching may be wet etching, dry etching, or a combinationthereof. In some embodiments, the auxiliary electrode 130 may be formedby using dry etching for precise patterning. In this case, in order toprevent damage to the first through third pixel electrodes 211, 212, and213, a conductive material of the auxiliary electrode 130 may include amaterial having an etch selectivity different from that of a material ofeach of the first through third pixel electrodes 211, 212, and 213.

Referring to FIG. 10, a side surface of the opening OP1 may be etched tohave an under-cut structure in which an upper portion of thepixel-defining layer 120 corresponding to the auxiliary electrode 130 isrecessed from the auxiliary electrode 130.

The etching for the under-cut structure may be dry etching. In thiscase, the photoresist pattern PR for forming the auxiliary electrode 130is not removed, such that a shape of the auxiliary electrode 130 may bemaintained and the side surface of the opening OP1 of the pixel-defininglayer 120 may be etched inwardly beyond an end of the auxiliaryelectrode 130.

A gas for the dry etching may be oxygen plasma, SF₆, CHFx, or Cl-basedgas. For example, when the pixel-defining layer 120 is formed of anorganic material, the dry etching may be performed by using oxygenplasma. When the pixel-defining layer 130 is formed of an inorganicmaterial, the dry etching may be performed by using SF₆.

Forming of auxiliary electrode 130 and forming the under-cut structureof the pixel-defining layer 120 may be sequentially performed bychanging only an etching condition in the same chamber and using thesame photoresist pattern.

Referring to FIG. 11, after the under-cut structure of thepixel-defining layer 120 is formed, the photoresist pattern PR isremoved.

Referring to FIG. 12, a first masking layer 1010 having an open portioncorresponding to the first pixel area PA1 may be formed. The firstmasking layer 1010 may include a first photoresist pattern layer 1210and a first auxiliary layer 1110 between the first photoresist patternlayer 1210 and the pixel-defining layer 120.

In some embodiments, the first masking layer 1010 may be formed by usingthe following process.

A non-photosensitive organic material layer may be formed on thesubstrate 100 on which the auxiliary electrode 130 is formed, and then aphotoresist layer may be formed on the non-photosensitive organicmaterial layer. The non-photosensitive organic material layer mayinclude, for example, a fluorine-based material. The photoresist layermay include a positive photosensitive material.

The first photosensitive pattern layer 1210 having a first openingportion OR1 may be formed by exposing and developing a portion of thephotoresist layer corresponding to the first pixel area PA1. A firstauxiliary opening portion AOR1 may be formed by etching a portion of thenon-photosensitive organic material layer exposed through the firstopening portion OR1. The first auxiliary opening portion AOR1 of thefirst auxiliary layer 1110 may be formed by etching such that the firstauxiliary opening portion AOR1 is greater than the first opening portionOR1.

The first auxiliary layer 1110 may be located on the auxiliary electrode130 such that an end portion of the auxiliary electrode 130 (e.g., anend portion of the auxiliary electrode 130 adjacent to the first pixelelectrode 211) is exposed and not covered.

Referring to FIG. 13, the first intermediate layer 221 and the firstcounter electrode 231 may be sequentially formed on the substrate 100 onwhich the first masking layer 1010 is formed. A passivation layer may befurther formed on the first counter electrode 231. Materials of thefirst intermediate layer 221 and the first counter electrode 231 havebeen described with reference to FIG. 3, and thus an explanation thereofwill not be repeated and the following will focus on the process offorming the layers.

The first intermediate layer 221 and the first counter electrode 231 maybe formed by using thermal evaporation. Deposition materials for formingthe first intermediate layer 221 and the first counter electrode 231 maymove toward the substrate 100 in a direction perpendicular or oblique tothe substrate 100. Accordingly, an end portion of the first intermediatelayer 221 and an end portion of the first counter electrode 231 mayextend into a space under the first photosensitive pattern layer 1210without contacting the first auxiliary layer 1110. As the depositionmaterials are deposited in an oblique direction, the end portions of thefirst intermediate layer 221 and the first counter electrode 231 mayeach have a forward taper shape. The end portion of the first counterelectrode 231 may extend farther than the end portion of the firstintermediate layer 221 and may contact the auxiliary electrode 130 suchthat the first counter electrode 231 has a width greater than that ofthe first intermediate layer 221. The first counter electrode 231 maydirectly contact a top surface of the auxiliary electrode 130 and may bedirectly connected electrically to the auxiliary electrode 130.

Referring to an enlarged view of FIG. 13, the first intermediate layer221 may include the lower functional layer 221 a, the emission layer 221b, and the upper functional layer 221 c. The lower functional layer 221a, the emission layer 221 b, and the upper functional layer 221 c may besequentially deposited. The pixel-defining layer 120 may have theunder-cut structure in which an upper portion of the pixel-defininglayer 120 is recessed from the auxiliary electrode 130. Accordingly, aportion of the lower functional layer 221 a may be deposited over theauxiliary electrode 130 and a portion of the lower functional layer 221a may be deposited inside the opening OP1 such that the portion of thelower functional layer 221 a deposited over the auxiliary electrode 130and the portion of the lower functional layer 221 a inside the openingOP1 are spaced apart from each other.

Portions of the emission layer 221 b and/or the upper functional layer221 c may also be spaced apart from each other according to a size ofthe under-cut structure of the pixel-defining layer 120 and a thicknessof the auxiliary electrode 130.

Referring to FIG. 14, the first masking layer 1010 may be removed by alift-off process. In an embodiment, when the first auxiliary layer 1110is formed of a fluorine-based material, the first auxiliary layer 1110may be removed by using a fluorine-based solvent. When the firstauxiliary layer 1110 is removed, the first photosensitive pattern layer1210 on the first auxiliary layer 1110 and material layers stacked onthe first photosensitive pattern layer 1210 are also removed. The firstintermediate layer 221 and the first counter electrode 231 having islandshapes may remain on the first pixel area PA1.

Referring to FIG. 15, a second masking layer 1020 having an open portioncorresponding to the second pixel area PA2 may be formed. The secondmasking layer 1020 may include a second photosensitive pattern layer1220 and a second auxiliary layer 1120 between the second photosensitivepattern layer 1220 and the pixel-defining layer 120. The secondauxiliary layer 1120 and the second photosensitive pattern layer 1220may by formed by using the same material and the same process asdescribed above with respect to the first auxiliary layer 1110 and thefirst photosensitive pattern layer 1210.

The second intermediate layer 222 and the second counter electrode 232may be sequentially formed on the substrate 100 on which the secondmasking layer 1020 is formed. A passivation layer may be additionallyformed over the second counter electrode 232. Materials of the secondintermediate layer 222 and the second counter electrode 232 have beendescribed with reference to FIG. 3, and thus a explanation thereof willnot be repeated.

The second intermediate layer 222 and the second counter electrode 232may be formed by thermal evaporation, and the passivation layer may beformed by chemical vapor deposition (CVD).

Deposition materials for forming the second intermediate layer 222, thesecond counter electrode 232, and the passivation layer may move towardthe substrate 100 in a direction perpendicular or oblique to thesubstrate 100. Accordingly, end portions of the second intermediatelayer 222, the second counter electrode 232, and the passivation layermay each have a forward taper shape without contacting the secondauxiliary layer 1120.

The end portion of the second counter electrode 232 may extend fartherthan the end portion of the second intermediate layer 222 and maycontact the auxiliary electrode 130 such that the second counterelectrode 232 has a width greater than that of the second intermediatelayer 222. The second counter electrode 232 may directly contact a topsurface of the auxiliary electrode 130 and may be directly connectedelectrically to the auxiliary electrode 130.

The second masking layer 1020 may be removed by using a lift-offprocess. For example, the second auxiliary layer 1120 may be removed byusing, for example, a fluorine-based solvent. Accordingly, the secondphotosensitive pattern layer 1220 on the second auxiliary layer 1120,the second intermediate layer 222, the second counter electrode 232, anda second passivation layer 242 may be removed. The second intermediatelayer 222, the second counter electrode 232, and the second passivationlayer 242 having island shapes may remain on the second pixel area PA2.

Referring to FIG. 16, a third masking layer 1030 having an open portioncorresponding to the third pixel area PA3 may be formed. The thirdmasking layer 1030 may include a third photosensitive pattern layer 1230and a third auxiliary layer 1130 between the third photosensitivepattern layer 1230 and the pixel-defining layer 120. The third auxiliarylayer 1120 and the third photosensitive pattern layer 1220 may be formedby using the same material and the same process as described above withrespect to the first auxiliary layer 1110 and the first photosensitivepattern layer 1210.

The third intermediate layer 223 and the third counter electrode 233 maybe sequentially formed on the substrate 100 on which the third maskinglayer 1030 is formed. A passivation layer may be additionally formedover the third counter electrode 233. Materials of the thirdintermediate layer 223, the third counter electrode 233, and thepassivation layer have been described with reference to FIG. 3, and thusa explanation thereof will not be repeated.

The third intermediate layer 223 and the third counter electrode 233 maybe formed by using thermal evaporation, and the passivation layer may beformed by using CVD.

Deposition materials for forming the third intermediate layer 223, thethird counter electrode 233, and the passivation layer may move towardthe substrate 100 in a direction perpendicular or oblique to thesubstrate 100. Accordingly, end portions of the third intermediate layer223, the third counter electrode 233, and the passivation layer may eachhave a forward taper shape without contacting the third auxiliary layer1130.

The end portion of the third counter electrode 233 may extend fartherthan the end portion of the third intermediate layer 223 and may contactthe auxiliary electrode 130 such that the third counter electrode 233has a width greater than that of the third intermediate layer 223. Thethird counter electrode 233 may directly contact a top surface of theauxiliary electrode 130 and may be directly connected electrically tothe auxiliary electrode 130.

Referring to FIG. 17, the third masking layer 1030 may removed using alift-off process. For example, the third auxiliary layer 1130 may beremoved by using, for example, a fluorine-based solvent. Accordingly,the third photosensitive pattern layer 1230 on the third auxiliary layer1130 and material layers may be removed. The third intermediate layer223 and the third counter electrode 233 having island shapes may remainon the third pixel area PA3.

FIG. 18 illustrates a cross-sectional view of an organic light-emittingdisplay apparatus according to another embodiment. In FIG. 18, elementsthat are the same as those in FIG. 3 are denoted by the same referencenumerals, and thus a explanation thereof will not be repeated.

In the present embodiment, in the organic light-emitting displayapparatus, a thin-film encapsulation layer 300 that helps to preventexternal oxygen and moisture from penetrating into the display area DAby sealing the display area DA may be formed.

The thin-film encapsulation layer 300 may include at least one inorganicfilm (e.g., first and second inorganic films 310 and 330) and at leastone organic film 320. For example, the thin-film encapsulation layer 300may include the first inorganic film 310, the organic film 320, and thesecond inorganic film 330 that are sequentially stacked as shown in FIG.18. In some implementations, the thin-film encapsulation layer 300 mayhave any of various other configurations.

Each of the first inorganic film 310 and the second inorganic film 330may include at least one material selected from the group consisting ofsilicon nitride, aluminum nitride, zirconium nitride, titanium nitride,hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide,titanium oxide, tin oxide, cerium oxide, and SiON.

The organic film 320 may include at least one material selected from anacrylic resin layer, a methacrylic resin layer, polyisoprene, avinyl-based resin layer, an epoxy-based resin layer, a urethane-basedresin layer, a cellulose-based resin layer, and a perylene-based resinlayer.

The thin-film encapsulation layer 300 may formed on the first throughthird OLEDs OLED1, OLED2, and OLED3 as illustrated in FIG. 18. In someimplementations, the organic light-emitting display apparatus mayinclude a sealing substrate instead of the thin-film encapsulation layer300. The sealing substrate may be adhered to the substrate 100 by usinga sealing member such as a sealing glass frit. The sealing substrate mayhelp to prevent external moisture or air from penetrating into thedisplay area DA.

In some implementations, various functional layers such as apolarization layer, a color filter layer, and a touchscreen layer may befurther located over the thin-film encapsulation layer 300 or thesealing substrate.

By way of summation and review, when an organic light-emitting displayapparatus is manufactured, light of different colors may be emitted frompixel areas. A counter electrode integrally formed over a plurality ofpixels and an emission layer of each pixel may be formed by using adeposition mask. As the resolution of an organic light-emitting displayapparatus increases, a width of an open slit of a mask used during adeposition process decreases and a reduction of a distribution thereofis desirable. Also, in order to manufacture a high-resolution organiclight-emitting display apparatus, it is desirable to reduce or eliminatea shadow effect. Research has been conducted on a deposition process ofpatterning a sacrificial layer and using the patterned sacrificial layeras a mask.

Embodiments include an organic light-emitting display apparatus forreducing a defect rate of an organic light-emitting device (OLED) and amethod of manufacturing the organic light-emitting display apparatus.

As described above, in an organic light-emitting display apparatusaccording to the one or more embodiments, when a pixel-defining layerhas an under-cut structure in which an upper portion of thepixel-defining layer is recessed from an auxiliary electrode, leakagecurrent between a counter electrode and a pixel electrode may beprevented.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope thereof as set forth in thefollowing claims.

What is claimed is:
 1. A method of manufacturing an organiclight-emitting display apparatus, the method comprising: providing asubstrate on which a plurality of pixel electrodes are formed; forming apixel-defining layer including a cover portion and openings, wherein thecover portion covers an edge of an adjacent pixel electrode from amongthe plurality of pixel electrodes, and the openings respectively exposea central portion of each of the plurality of pixel electrodes; formingan auxiliary electrode such that the auxiliary electrode corresponds toat least a portion of a top surface of the cover portion; forming, byetching a side surface of the cover portion, an under-cut structure inwhich the at least a portion of the top surface of the cover portion isrecessed from the auxiliary electrode; and forming a first masking layersuch that a first pixel electrode from among the plurality of pixelelectrodes is exposed, and then forming, on the first pixel electrode, afirst intermediate layer and a first counter electrode.
 2. The method asclaimed in claim 1, wherein forming the auxiliary electrode and formingthe under-cut structure are performed using a same photoresist pattern.3. The method as claimed in claim 1, wherein: the pixel-defining layerincludes an organic material, and etching the side surface of the coverportion is performed by dry etching using an oxygen plasma.
 4. Themethod as claimed in claim 1, wherein: the pixel-defining layer includesan inorganic material, and etching the side surface of the cover portionis performed by dry etching using a SF₆ gas.
 5. The method as claimed inclaim 1, wherein: the first intermediate layer includes an emissionlayer, a lower functional layer located under the emission layer, and anupper functional layer located over the emission layer, and a thicknessof the auxiliary electrode is greater than a thickness of the lowerfunctional layer.
 6. The method as claimed in claim 1, wherein: thefirst intermediate layer includes an emission layer, a lower functionallayer located under the emission layer, and an upper functional layerlocated over the emission layer, at least a portion of the firstintermediate layer is located over the auxiliary electrode, and at leasta portion of the lower functional layer located over the auxiliaryelectrode is spaced apart from a portion of the lower functional layerlocated inside the openings.
 7. The method as claimed in claim 6,wherein the lower functional layer includes at least one of a holeinjection layer and a hole transport layer.
 8. The method as claimed inclaim 1, wherein an end portion of the first counter electrode extendstoward and contacts the auxiliary electrode.
 9. The method as claimed inclaim 1, further comprising: removing the first masking layer by alift-off process; forming a second masking layer such that a secondpixel electrode from among the plurality of pixel electrodes is exposed;forming, on the second pixel electrode, a second intermediate layer anda second counter electrode; removing the second masking layer by alift-off process; forming a third masking layer such that a third pixelelectrode from among the plurality of pixel electrodes is exposed; andforming, on the third pixel electrode, a third intermediate layer and athird counter electrode.
 10. The method as claimed in claim 1, whereinthe substrate includes a plurality of thin-film transistors (TFTs)electrically connected to the plurality of pixel electrodes.